“Kuleshov’s principle started from the idea that each shot is like a building block and that each shot derives its meaning from its context.” 
The Kuleshov effect implies that a shot only has meaning in relation to the shots either side of it. A close up shot of someone’s emotional reaction for example is meaningless (or is at least uninteresting) unless we know the context of their reaction. We must be given a reason to emphasise with them.
As Bordwell observes,  the basis of Hitchcock’s Rear Window can be simply thought of as shots of Jeff looking out his window, his point of view, and then his reaction. As we never see an establishing shot of both Jeff, and what he is looking at, much of the thrill of Rear Window lies in the anticipation of the reaction shot in relation to its preceding action shot or vice versa. Hitchcock and editor George Tomasini often play with this idea, alternating between fast paced cuts and longer, prolonged shots in order to tease the audience and dictate the tension and relief they feel.
Editing can be used to shift the emphasis of a shot to a particular character or action. With dialogue, emphasis can be placed with either the speaker, or the listener and their reaction depending on which the director or editor feels is the most important aspect of a scene. As Orpen notes , in Rear Window Hitchcock often achieves this by using jarring jump cuts and close ups (often infringing the 30 degree rule) rather than use a traditional reverse-angle cut. In a conversation between Jeff and Stella, where Jeff is troubled and anxious about his relationship with Lisa, Jeff says: “She expects me to marry her”, to which Stella answers: “That’s normal.” Here, the emphasis is placed not on Stella’s statement, but on Jeff’s reaction as we cut to a close up of Jeff. This, in turn leads us to emphasize with Jeff and his view of marriage, rather than Stella’s.
Another technique is the use of long takes, a singular, continuous take with no lack of cuts, often lasting several minutes. These generally stand out as they can interrupt the pacing of the film. A recent example is Alfonsa Cauron’s 2006 film Children of Men. Two memorable examples are the four minute long car chase shot, and the ten minute long ‘Uprising’ scene, which contains a single cut.
In the car chase shot, a car is driving through a woodland road before being attacked by a large group of protesters and pursued by a motorcyclist who shoots Julianne Moore’s character who is sitting in the passenger seat. Before the ‘action’ of the scene starts we are shown a minute and a half of not very much at all. The camera rotates 360 degrees inside the car, showing all of the characters talking and joking. This helps to emphasise the contrast between between calm and serenity, and chaos, without the need for fast paced cuts or music. The Uprising scene follows the protagonist through a war zone. The slow pacing of this scene not only gives a sense of the massive scale of the area, but adds a shocking realism to content of the scene. We feel like we are following Clive Owen’s character, hiding with him, avoiding crossfire with him, and under attack ourselves rather than just watching him and what is happening to him. Without a visual cut to distract out eyes to something else, we are constantly aligned with the protagonists and feel the same panic and claustrophobia that they feel.
Another reason why these shots are particularly effective, aside from their technical and aesthetic qualities is their apparent lack of editing. Traditional continuity editing means that the audience has developed an expectation of cinema. Anticipation of a cut that doesn’t come, or prolonged tension without relief can be terribly intense and exhilarating. With traditional action scenes like these we might have instead expected fast paced cuts and lots of matches on action (which may also have been effective), but with this irregularity and change from what we are familiar with, we are drawn further into the film.
 Susan Hayward (2002), Cinema Studies: The Key Concepts (London: Routledge), p.338.
 David Bordwell and Kristin Thompson, ‘The Relation of Shot to Shot: Editing’ in David David Bordwell and Kristin Thompson, Film Art: An Introduction 4th ed. (New York:University of Wisconsin Press/McGraw Inc., 1993) pp. 246-288.
 Extract from Valerie Orpen, Film Editing: The Art of the Expressive (London: Wallflower, 2002).